The present invention relates to a composite polymeric electrolyte, in particular for use in light-weight electrochemical accumulators.
At the present state of art, the use of complex compounds formed of polymeric components, e.g. lithium salts, such as electrolytic membranes for manufacturing electrochemical thin-layer devices (for example accumulators or optical detectors) is known. The use of such complex compounds is, however, limited in part by the operating temperature generally higher than 80.degree. C. and by chemical reaction to the used electrode materials, in particular to lithium. The high temperature is bound to the transport mechanism which requires a polymeric structure having an amorphous state to a certain extent which is reached only above 80.degree. C. in the known systems.
The reactivity to the electrode materials is bound to the presence of impurities (for example, water and/or solvents having low boiling points) which can hardly be eliminated by means of simple purification systems. It is then very important to find alternate materials leading to an increase of the electrical conductivity and thermal stability of the polymeric electrolytes.